Free STL viewer for your browser
Drag any .stl file into the browser to see it. No upload, no signup, no install. Works the same on iPhone, Android, and desktop.
What you can do with it
- Open both ASCII and binary STL files
- Orbit, pan, zoom with mouse or touch
- Measure real-world distances in millimetres
- Cross-section any axis to inspect interiors and wall thickness visually
- Solid, wireframe, X-ray and matte view modes
- Print-readiness sniff test — manifold check, overhang count, bed fit against Bambu A1 / Prusa MK4 / Ender 3 / Bambu X1C
- Capture a screenshot or a rotating GIF for sharing
- AR view on phone — place the print at real scale in your room before you commit filament
Why open STL in the browser instead of a slicer
Slicers are made for the moment right before you press print. They are heavy to install, slow to launch, and overkill if you just want a quick look at a model you downloaded from Thingiverse, Printables, MakerWorld, or a Patreon studio.
The viewer at open3d.app is the opposite: a tab that opens in a second, takes a file by drag-and-drop, and shows you what you have. Useful before downloading hundreds of megabytes of STLs you may not even like, before slicing, or on a phone away from your workstation.
Privacy: nothing leaves your device
The viewer is a static page. Your file is read by your browser, decoded by JavaScript on your device, and drawn to a canvas. Nothing crosses the network. Open your browser's network tab while dropping a file in and you will not see a single upload request.
FAQ
Is the STL viewer really free?
Yes. The web viewer is completely free with no ads. The phone and Windows apps are also free, supported only by a small banner ad on mobile. There is no pay-to-unlock, no premium tier, no "remove ads" upsell.
Does my STL get uploaded anywhere?
No. Your STL file is read by your browser and rendered locally on your device. Nothing crosses the network. You can verify this in your browser's network tab.
Does it support both ASCII and binary STL?
Yes. Both formats are auto-detected and loaded. Binary STL files are usually smaller and slightly faster to parse.
How large an STL can I open?
Most browsers handle files up to about 250 MB comfortably. Larger files still work but may load more slowly on lower-end phones.
Can I check if the STL is printable?
There is a quick sniff test for manifold geometry, overhang count, and bed fit against common printers. It is a heuristic, not a slicer — always also check in Cura, Bambu Studio, or PrusaSlicer before printing the real thing.
Does it work on an iPhone or Android phone?
Yes. Open open3d.app in your phone's browser and drop a file in, or install the iOS / Android app for offline use.